1. Field of the Invention
The present invention is directed generally to a method and apparatus for mining, and, more particularly, to a method and apparatus for rotary mining.
2. Description of the Background
In conventional mining, different techniques are employed to remove the desired subterranean material. One technique that is commonly employed for mining coal from seams that are relatively deep beneath the surface involves a network of underground shafts and passages. Sophisticated and expensive mining machinery loosens the material and transports the material to the surface, but personnel are required to work with them in dangerous underground conditions.
Another technique, known as strip or surface mining, is used to remove valuable material from seams that are relatively close to the surface. In strip mining, dirt, rocks, gravel, etc., referred to as overburden, are removed above a coal seam to expose the seam. However, strip mining also requires the use of expensive machinery to remove the overburden and the material. Furthermore, because the overburden is removed above the seam, strip mining has an adverse environmental impact on the area being mined and returning a strip mine site to its original condition can be costly. Strip mining also has the disadvantage that it may not be economically feasible to remove the overburden above deep portions of a seam that varies in depth. Such a situation may dictate the use of expensive highwall mining techniques that are designed to remove the material from the deep portion of a seam when removal of overburden is no longer economically feasible. In this technique, a mining apparatus is placed on a bench in the strip mine and mining and conveying apparatuses are propelled into the seam in parallel entries. Thus, there is a need for a method and apparatus to remove relatively shallow subterranean material, such as coal from a coal seam, without having to remove the overburden from atop the material and without having to employ expensive machinery.